The present invention relates to an apparatus and equipment for manipulating liquids particularly for the growth of crystals under zero or near zero gravity conditions such as in outer space.
The growth of crystals in outer space has been practiced and is further considered on a program basis as shown for example in U.S. Pat. No. 4,886,646 or in the Journal of Crystal Growth, volume 76, 92 respectively on pages 681 et seq and 581 et seq. Generally it has been found to be of advantage to use for example a protein solution for the crystal growth and to keep separate therefrom the precipitating medium prior to and during the transport of these media into outer space to keep them separate until crystallization is desired for obtaining crystal growth these two media are blended. In the so called hanging drop method a drop or droplet is suspended from one side and is comprised of unsaturated solution with an initial volume of V1. Through appropriate steps the liquid is gradually evaporated; of course not completely but such that its volume is reduced to V2 thus there will be a desired supersaturation that leads to the crystallization of that substance. Further to the state of the art, the above mentioned patent also alludes to other crystal growth methods such as diffusive method using a dialysis bag.
This hanging drop method of course has been practiced on Earth under gravity conditions but it is apparent that on practicing this method in outer space under zero gravity or at least under reduced gravity conditions the drops that can be produced and be suspended (before dropping) can be much larger and that in turn means that larger crystals can be grown in this environment. Earth bound crystal growth e.g. of the hanging drop method or otherwise an outer space equipment must meet the following requirement and/or has to have the following features.
Whatever media are involved they will be tightly sealed prior to the beginning of the crystal growth and manipulation. The droplet itself should be produced on demand but automatically i.e. without manual manipulation. Most importantly after the process has been completed the liquid has to be returned to a tightly vacuum sealed condition under avoidance of gas bubbles or other voids i.e. a residual droplet must be retracted into some kind of container and fill it completely since otherwise the crystal grown therein, if of a delicate nature, may not survive the landing.